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Oct 13, 2004Keywords:
Ilmenite titanite petrochemistry granite gneiss Abeokuta
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Petrochemistry of opaque minerals in biotite granite gneiss of Abeokuta area Southwestern Nigeria
Abstract
Oxide minerals, notably ilmenite and titanite occurring in the biotite granite gneiss of Abeokuta area, southwestern Nigeria, were analysed using an electron microprobe with a view to contribute to the existing knowledge on the petrogenesis of the rock.
Ilmenite occurs as idiomorphic euhedral crystals in the biotite granite gneiss. Compositionally, it belongs to the ilmenite-pyrophanite series consisting of about 94mol.% FeTiO3, 5mol.% MnTiO3 and 1mol.% MgTiO3. It constitutes about 80% of the opaque minerals in the rock. Grey, wedge-shaped prisms of titanite were observed in close association with pyrite. Other opaque minerals present include pyrrhotite, which is associated with chalcopyrite and covellite.
Petrography and chemical data of the ilmenites and titanites suggest that the protoliths of the biotite granite gneiss are mainly igneous. These chemical data can also serve as petrogenetic discriminator, particularly in a polymetamorphic terrain.
KEY WORDS: Ilmenite; titanite; petrochemistry; granite gneiss; Abeokuta
Global Journal of Geological Sciences Vol.2(2) 2004: 163-170
Ilmenite occurs as idiomorphic euhedral crystals in the biotite granite gneiss. Compositionally, it belongs to the ilmenite-pyrophanite series consisting of about 94mol.% FeTiO3, 5mol.% MnTiO3 and 1mol.% MgTiO3. It constitutes about 80% of the opaque minerals in the rock. Grey, wedge-shaped prisms of titanite were observed in close association with pyrite. Other opaque minerals present include pyrrhotite, which is associated with chalcopyrite and covellite.
Petrography and chemical data of the ilmenites and titanites suggest that the protoliths of the biotite granite gneiss are mainly igneous. These chemical data can also serve as petrogenetic discriminator, particularly in a polymetamorphic terrain.
KEY WORDS: Ilmenite; titanite; petrochemistry; granite gneiss; Abeokuta
Global Journal of Geological Sciences Vol.2(2) 2004: 163-170
